1,3,2-Diazaphospholidine compounds

ABSTRACT

Novel compounds represented by the structure   where all R substituents are identical and are methyl or ethyl. The compounds are useful as durable fire retardants for cellulosic materials.

United States Patent [191 Schenkenberg et al.

[ 1 Oct. 7, 1975 1,3,2-DlAZAPHOSPHOLlDINE COMPOUNDS [75] Inventors: Philip R. Schenkenberg, Glendale;

Charles R. Williams, St. Louis, both of Mo,

[73] Assignee: Monsanto Company, St. Louis, Mo,

[22] Filed: Sept. 12, 1974 [2l} Appl. No.: 505,392

OTHER PUBLICATIONS Z-Alkylamino-Z-oxo-l ,3-diaza-2-phosphacyclopentanes," Ozaki et al., CA 78zl4797lm (1973),

Primary ExaminerDaniel E. Wyman Assistant Examiner-Thomas A. Waltz Attorney, Agent, or FirmWil|iam H. Duffey 5 7] ABSTRACT Novel compounds represented by the structure where all R substituents are identical and are methyl or ethyl. The compounds are useful as durable fire retardants for cellulosic materials.

4 Claims, No Drawings l ,3,2-DIAZAPHOSPHOLIDINE COMPOUNDS This invention relates to novel phosphorus-nitrogen ring compounds useful as durable fire retardants for cellulosic materials. These compounds are represented by the structure R-lTl lT-R H H 2. 1..

where all R substituents are identical and are methyl or ethyl.

The novel compounds of this invention can be prepared by the reaction of a trialkylphosphoric triamide and aqueous glyoxal at a ph of about 7 with moderate heating. In a preferred embodiment, trimethylphosphoric triamide (abbreviated as TPA") is employed, resulting in a product wherein the R" group of the above structure is methyl, the product being 1,3- dimethyl-Z-methylamino-2-oxo-4,5-dihydroxy-1,3,2- diazaphospholidine.

The TPA reactant employed herein was prepared by a modification of the method of Holmes. The latter is described in Inorganic Chemistry, I, 89 (1962) by Robert R. Holmes and James A. Forstner. After adding an excess of dry methylamine to a cold (approximately 35C.) solution of POCl in heptane, the product was extracted with 3 equivalents of aqueous sodium hydroxide. thereby neutralizing the amine hydrochloride. After separation from the heptane, the aqueous solution was concentrated, filtered, concentrated additionally and refiltered to arrive at a solution which was 70% TPA, 7% NaCl, 2 to 5'72 hydrolysis products of TPA and water. With the exception of precipitates. viz., Na P O or hydrates thereof, formed by further hydrolysis of the impurities, this solution was stable. Pure, crystalline TPA was obtained by azeotropic drying of the agueous solution with chloroform followed by filtration to remove salts, concentration and a double crystallization of the solute. Yield of the crude aqueous solution was generally 80 to 90% A yield as high as 70% was observed for the purification step, affording a product that melted at from 105 to l 10C. This product could be sublimed in vacuum with no apparent improvement in purity.

A typical preparation of the monohydrate of 1,3- dimethyl-2-methylamino-2-oxo-4,S-dihydroxy-l ,3,2- diazaphospholidine is set forth in the following example.

EXAMPLE I Filtered 40% aqueous glyoxal 159 g.) was weighed into a 500 milliliter flask. The flask was equipped with a magnetic stirring bar, a thermometer and a pH electrode which had been standardized against pH 7 bufier. The pH of the solution was adjusted to 7.0 with a 50% aqueous sodium hydroxide solution. TpA (150 g.) was then added to the flask and the pH was maintained at 7.0, with stirring. The pale yellow solution was then heated slowly to 65C. with dropwise addition of sodium hydroxide to maintain the pH at 7.0. The contents were held at this temperature for 8 minutes and then quenched in ice to 25C. The solution was still pale yellow but no solid formed until after 3 to 4 hours. The crystals were filtered and washed with small quantities of an %/20% tetrahydrofuran/ethanol solution and dried in a nitrogen stream. With 98 g. of product recovered, this amounted to a 42% yield based on 233 g. theory for TABLE 1 below summarizes the analyses of the initial product and the recrystallized product.

TABLE I Elemental Analyses Theory Found Found Element (monohydrate) (initially) (recrystallized) P l) 14.55 14.49 14.49 N (3) 19.72 19.55 19.33 C (5) 28.72 28.13 28.00 H( 16) 7.5l 7.66 7.60 [O(3)]* 30.05 (30.16) (30.58) Melting 106-1 l5C. 107-115C. Point By difference In preparing a compound of this invention where R is ethyl, triethylphosphoric triamide instead of TPA is reacted with aqueous glyoxal according to the procedure of EXAMPLE 1 above.

The phosphorus-nitrogen ring compounds of the present invention, in both the hydrated and the anhydrous form, are useful as treating agents for imparting fire retardance to cellulosic materials such as textile fabrics.

The exact manner of treating cellulosic substrates with novel compounds of this invention is not critical. It is generally desired that the cellulosic material be impregnated with the phosphorus-nitrogen ring compound from an aqueous medium. Although the use of an aqueous medium is preferred, particularly within the textile industry, organic media such as hydrocarbons, alcohols, ethers, amides and the like are sometimes uti lized.

According to conventional standards, a flame retardant or flame resistant cellulosic material is one where, although the surface or article may burn when in direct contact with a flame source, the flame will extinguish when the source is removed rather than continue to propagate.

Thus, the amount of phosphorus-nitrogen ring compound which is applied to the cellulosic substrate must be sufficient to render the substrate flame resistant. As a general rule, about l.()% or more by weight of phosphorus, based upon the weight of the cellulosic substrate, will render the substrate flame retardant.

ln flame retarding a cellulosic substrate with the phosphorus-nitrogen ring compounds of the present invention, the substrate (fabric) is passed through a bath comprising an aqueous solution of the compound and thereafter cured at a temperature above 100C, preferably from 120C. to 200C. for a period of 1 minute to 1 hour, the latter duration depending upon cure temperature and other variables.

It is usually found desirable to employ a latent acid catalyst in aqueous solution with the phosphorusnitrogen -ring compound. Non-limiting examples of such catalysts are magnesium chloride and 2-amin0-2- methylpropanol-l-hydrochloride. The catalyst may be typically present in about 1 percent by weight of the aqueous solution which comprises the bath for treating the cellulosic substrate.

Resin type coreactants are often desirable in conjunction with phosphorus-nitrogen compounds of the present invention. They are typically present in about 5 percent by weight of the bath solution although considerable variation is permissible in this concentration. Non-limiting examples of suitable coreactants include substituted melamines. guanamines and dimethylol cyclic alkylene ureas. Suitable substituted melamines include the methylol melamines such as diand trimethylol melamines and modified methylol melamines such as the trimethyl ether of trimethylol melamine.

What is claimed is: l. A compound represented by the structure R-N NR where all R substituents are identical and are methyl 0 ethyl.

2. A compound represented by the structure UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3 911 005 DATED 1 October 7, 1975 INVENTOMS) 3 Philip R. Schenkenberg and Charles R. Williams It is certified that error appears in the aboverdentified patent and that said Letters Patent are hereby corrected as shown betow;

Col. 1, line 21, "ph" should be pH Col. 1, line 44, "aqueous" should be aqueous Col. 1, line 63, "TpA" should be TPA Claim 2, correct structure to read O N R Pt R 11] N R H20 ac CH OH OH Signed and Bealcd this thirtieth Day of Dewmber 1975 [SEAL] Attesr:

RUTH C. MASON C. 'Amflll. DAN" Arresting Officer Commissioner of hmm and Trademarks 

1. A COMPOUND REPRESENTED BY THE STRUCTURE
 2. A compound represented by the structure
 3. A compound of claim 1 wherein R is methyl.
 4. The compound 1,3-dimethyl-2-methylamino-2-oxo-4,5-dihydroxy-1,3,2-diazaphospholidine. 